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[deleted] t1_iy3rq6q wrote

Reply to comment by westbamm in 'Landmark achievement': Rolls-Royce and easyJet hail successful hydrogen jet engine test by Wagamaga

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jdmgto t1_iy463xm wrote

Cryogenic hydrogen is just an ungodly pain in the ass to work with which is why every non-rocket utilization of hydrogen as a fuel uses pressurized gaseous hydrogen instead. First off the energy usage to create the hydrogen, then chilling it to just a few degrees above absolute zero, then trying to maintain it is just ridiculous.

As far as aircraft, the problem becomes insulation and boil off. The wings of a conventional commercial aircraft aren’t thick enough to store any significant amount of cryogenic hydrogen once you factor in insulation. Never mind trying to keep it chilled in what amounts to a giant radiator. That leaves the body of the aircraft which is, you know, where you put the people and the cargo. You’re losing a lot of your money making space filling it with fuel tank. Never mind the operational problems of cryogenic hydrogen, even the best tanks boil off hydrogen constantly, in flight, everywhere. Rockets can get away with it because they can constantly top off the tanks while they wait to launch then only operate for minutes. An airliner has to operate for hours, and might even be waiting to take off for hours. I’m just imagining a cryogenic airliner stuck on the tarmac in Dubai waiting to take off.

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[deleted] t1_iy46qhn wrote

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jdmgto t1_iy49rgc wrote

First off, they’re loading those hydrogen tanks into the area the Dash 8 uses for cargo and it looks like a couple rows of seats to boot. They’re gonna lose even more seats because people aren’t going to be ok with a “no luggage” rule on their flight. Second, the normal range of a Dash 8 is two to nearly three times that. I know the three things airlines are always willing to give up on are cargo volume, passenger count, and range. Also, one conspicuous detail I didn’t see in the article is anyone asking the FAA if they’re ok with this idea and I just can’t help but think they might have a little tiny problem loading up six tanks into the back of a passenger plane, the failure of any of which will literally blow the aircraft in half.

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[deleted] t1_iy4addj wrote

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jdmgto t1_iy4ggr4 wrote

Because when it comes to its use as a fuel that is hydrogen’s only positive. The negatives include the collapse of global air travel back into the domain of the wealthy alone. Global air travel’s piece of the global warming pie is only about 3% which is not insignificant but it’s also not what’s killing our planet. You know what does have tremendous benefits, minimal if no downsides and even some upsides for consumers, and will have dramatically bigger GHG savings? Electrification of railways and vehicles, improving public transit, and transitioning to nuclear power.

Yeah, a 1,200 liter, 10,000 psi tank catastropic failure, I’m absolutely sure you’re right and that flying tin can will tank that like a boss. I'm sure there's absolutely no test footage of much, much smaller tanks turning the back end of cars into so much confetti.

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E_Snap t1_iy40400 wrote

Which requires enormous amounts of heavy insulation on aircraft fuel tanks and actively cooled cryogenic plants at airports.

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